Maps are having a moment. Geography is in the air. Apple is fighting it out with Google Maps; since the election the Blue States are still battling the Red, and who knew there was a floodplain map of Manhattan before Sandy? Foreign correspondent Robert D. Kaplan distills the world’s geopolitical perplexities into maps in his latest book, which he calls The Revenge of Geography.

Maybe we are feeling somewhat lost, and it’s not the revenge, but the reassurance, of geography we seek. A map, after all, is synonymous with a plan, a design, a guide. Maps are comfortably old-fashioned facts. They seem so quaint, yet so indubitable. But the occupational secret of the cartographers’ guild is that every map is a statement about a place, not the place itself. It may be an experimental hypothesis, a personal essay, or outright propaganda, but a map is always a proposition about reality, not its “truth.”

The exhibition “First X, Then Y, Now Z: Landmark Thematic Maps,” at Princeton University, is a beautiful collection of maps of a sort that once were considered strictly utilitarian. The antiquarian style–these maps were handcrafted, lettered and inked by artisans–corresponds with their antiquarian scientific content, which is racist and imperialist but mostly just plain wrong. Perhaps that anachronism is the source of the curious tension between beauty and utility that makes old maps so attractive to thieves and other collectors. These maps are often beautiful as objects, questionable as science, reprehensible as ideology–and irresistible in a museum.

None of the hundred maps on display through February 10 in the Main Exhibition Gallery at the Firestone Library, was created as a work of art, or even with a strong aesthetic intent. These were the tools and instruments of a wide range of inquisitive people engaged in some serious pursuit other than art: census-takers, botanists, meteorologists, geologists. In the argot of cartography, they are thematic maps. What does that mean?

“A thematic map is simply a map of something somewhere,” writes curator John Delaney, somewhat unhelpfully, in the sumptuous and indispensable catalog. Maybe we could get a little more detail if we asked the alternative question: “What would a non-thematic map look like?” The practical answer, as embodied in this collection, is that a non-thematic map is a political map, a map of states and their boundaries. Thus, a thematic map displays data that might have a scientific or sociological purpose, but not a political end.

Arthur H. Robinson (1915-2004), the influential cartographer-philosopher to whom the catalog is dedicated, wrote an important book about the art of mapmaking in 1952. It was called The Look of Maps, and surprisingly, it has no illustrations. Robinson had his reasons. “The scientific special purpose map, ” as he described the thematic map, “rarely should be examined out of context, so to speak, for its raison d’etre determines or limits, to a considerable degree, its visual character.” He thought you should really only look at a geological map in a geology book, for example, because Its reason for being is geology.

“First X, Then Y, Now Z,” is nevertheless a happy occasion to look at a collection of thematic maps, because all these old maps now share a context: history. Whatever special purpose they served for their makers, they are now historical. The unwieldy title hints at the early history of thematic mapping — the topical layering (the “z” coordinate) onto geographic space (“x,y” ordered pairs). The Firestone Library possesses early, if not always the earliest, thematic maps in various disciplines, such as meteorology, geology, hydrography, natural history, medicine, and sociology/economics.

If that range of subjects sounds like a college catalog, rest assured: the exhibit doesn’t feel at all like school. On the rainy autumn afternoon I visited the dimly lit unlovely library, it was like sitting in a dusty attic paging through random yellowed volumes of The Book of Knowledge. The sewer system of early modern Paris. The great snowstorm of 1842. The upper reaches of the Amazon. Human languages and races around the world. I took the time to enjoy my browsing, and you too will want several hours. Reading maps is more work than looking at pictures. The visual impact of many maps is immediate, but some cartographical wonders will reveal themselves only after close and repeated reading.

One map that will catch your eye is the biggest: a copy of Williams Smith’s 1815 geological chart of most of the British Isles. The original is 9 feet tall and 6 feet wide: the facsimile in Princeton at half that size but still dominates the room. Simon Winchester calls this “The Map that Changed the World” in his book of that name; its seminal importance to the science of geology is that it’s the first map of what lies beneath the earth. But look at it, displayed as an artifact . Pink in the middle, stippled with blue and resting on green base. Smith made this map by hand, and you cannot doubt that an aesthetic impulse moved that hand.

Beautifully printed, if not hand-colored, are the pages of the 1874 Statistical Atlas of the United States. This groundbreaking collection of maps and charts presented the data gathered by census takers in 1870. Economist and statistician Francis Amasa Walker superintended that census, creating visualizations that might inspire today’s data designers. This was the first census to enumerate the freed slaves, and includes A Map Showing the Proportion of the Colored to the Aggregate Population. It is what experts call a choropleth map–the counties with more black residents are shaded a deeper blue. It looks like an ugly black-and-blue bruise on the body of the American nation.

The scars of race are still visible in a 1937 Greyhound Lines giveaway, “A Good-Natured Map of the United States, Setting Forth the Services of the Greyhound Lines.” The catalog notes that “the “good nature” of the map condones social and racial stereotypes that proliferate in the map’s pictorials–Native American Indians snake dancing, African-Americans picking cotton–all captioned with “down home” lingo.” Like every transportation map, it demonstrates not only how to get from here to there, but with cheerful hues, whimsical landmarks and local color, it signals American Unity and the casual racism of the era.

Unity in the midst of diversity was already the theme of “Europa poly glotta,” a 1741 language map of the world, dreamt up by theologian and philologist Gottfried Hensel. In the book for which these four maps provided illustratration, Hensel was trying to show how all languages derive from a common origin in Hebrew. The textual “legend” almost overwhelms these maps. The margins are crammed with the first lines of the “Our father,’ translated into local languages in a bewildering soup of local alphabets. The ideal of an “Adamic language” has been discredited. Language is more complex than that. Hensel’s arcane crowded maps chart a delightful attempt to see the world whole and simple–and the complex mess he made as he failed.

There is something clear and pure about water. Hydrography, which represents the depth and and flow of rivers, lakes and oceans, endows maps with a natural beauty. The “Hydrographical Map of Great Britain” (1849, August Petermann) in this show complements Smith’s better-known geological map; Petermann weaves a delicate web of pastel waterways that you could imagine floating above the bedrock of solid colors on Smith’s. Printed in bold color in Paris in 1845, this is among the rarest cartographic delicacies in Princeton. You have not seen this map on the Internet. Its coloring is essentially simple: water is blue, land is brown and cities are orange dots.

The loveliest map in the show is titled simply “Chart 10”, belying its importance as the first synoptic US weather map. Watching the Weather Channel, we take “synoptic” meteorology for granted. It’s a look at the weather of a large area at one moment in time. “Chart 10” is a standard weather map for the evening of February 3, 1842: hanging over the Eastern seaboard, blue blobs of clear sky, yellow clouds and green snow. It resembles a mobile of Joan Miró.. A more aesthetic title would be “Winter:” a pastel abstraction of that season’s cold winds and colors.

“First X, Then Y, Now Z” closes with a handful of maps under the clever heading “Fanta ‘Z’.” Some chart literary places, like Faulkner’s freehand drawings of Yoknapatawpha county, or Bunyan’s Pilgrim’s Progress. Others represent Utopia and other paradises, such as the Country of Love or the Land of Marriage.

Although they may seem out of place in an exhibit of early hematic maps; the catalog notes “they use fictional geography and/or shapes to illustrate or symbolize themes.” But while the “fictions” of the early thematic maps were not inspired by the mapmakers’ imaginative fancies, they nevertheless tell stories about strange people and faraway places.

The distinction between fact and fiction may work in literature, but not in geography. The most elementary geographical facts are fictions: the North Pole, the equator, any political border. Like photography, cartography inspires a naive belief in the reality of what’s depicted. We trust “photographic evidence” and accept the importance of a place that’s been “put on the map.” Looking back at the past, “First X, Then Y, Now Z” can enlighten us about the rhetoric and the power of modern cartography.